1. Field of the Invention
This invention relates to a method for surface treatment of an ink jet recording head which performs recording by permitting an ink which is the recording liquid to be discharged and fly as droplets through ink discharging openings and attaching the droplets onto a recording medium surface, and more particularly to a method for surface treatment of an ink jet recording head which covers the surface having ink discharging openings with a surface treating layer.
2. Related Background Art
The ink jet recording method performs recording by permitting droplets of a recording agent called ink and attaching them onto a recording member such as paper, etc. The method includes the so-called ink-on demand system.
According to such ink jet recording system, it is demanded for improvement of recording quality that the ink droplets should be attached on the required position of the recording surface, namely that the discharging direction of the flying droplets for recording should be constant, and the discharging speed also constant and the sizes of the flying droplets uniform.
However, in the ink jet recording head, when the surface having discharging openings is coarse or has flaws such as cracks or defects formed thereon, ink will be attached nonuniformly on the surface having discharging openings during continuous discharge of ink, whereby the ink is drawn nonuniformly when the ink is discharged through the ink discharging openings and released therefrom, and therefore the discharging direction and the discharging speed, and also the sizes of the ink droplets were varied to bring about lowering in recording quality. Also, in an ink jet recording head produced by the invention in which the ink discharging openings are constituted of different kinds of materials as disclosed in U.S. Pat. No. 4,417,251, since wettability with ink differ depending on the respective constituent materials, localization of ink is also liable to occur on the surface having ink discharging openings while discharging of ink is continued for a long time, whereby the problems as mentioned above will readily occur.
As the method for such drawbacks, there have been made a large number of proposals to provide uniformly a liquid repellent or liquid-compatible material on the surface having ink discharging orifices. However, when various points in manufacture, for example, cost, precision, yield, etc. are considered, no satisfactory product has been obtained under the present situation. In the other words, there is no method for sufficient surface treatment which can be uniformly and simply applied to ink discharging openings without entrance of a surface treating agent to the inner direction of ink discharging openings.